1. Field of the Invention
The present invention relates generally to a radio frequency (RF) proximity detection and identification system and method, and in particular, to a radio frequency (RF) proximity detection and identification system utilizing RF modulation.
2. Description of the Related Art
The Arbitron Company (Arbitron) is a world leader in the measurement of audience participation in the listening and viewing of radio and television broadcasts. The audience participation data (data) is of critical importance to the broadcast stations and their sponsors. Currently, the data is collected through paper diaries and electronic set-top frequency detection. Both technologies are prone to errors and provide a limited amount of useable information. In addition, there has been a tremendous increase in the use of digital formats for all types of multi-media broadcasts, so that the computer is also starting to play a major role in an individual's multimedia listening and viewing experience.
Arbitron has, therefore, developed a new and innovative technology called Critical Band Encoding Technology (CBET) that encompasses all forms of audio and video broadcasts in the measurement of audience participation. This technology dramatically increases the both the accuracy of the measurement and the quantity of useable and effective data across all types of signal broadcasts. CBET is an encoding technique that Arbitron developed and that embeds identifying information (ID code) within the audio portion of a broadcast. The encoding is done prior to broadcasting, i.e. at the broadcast station, and without audible distortion to the original audio signal. An audio signal is broadcast within the actual audio signal of the program, in a manner that makes the ID code inaudible, to all locations the program is broadcast, for example, a car radio, home stereo, television, etc. This embedded audio signal or ID code is then picked up by small (pager-size) specially designed receiving stations called Portable People Meters (PPM), which capture the encoded identifying signal, and store the information along with a time stamp in memory for retrieval at a later time. A microphone contained within the PPM receives the audio signal, which contains within it the ID code.
Arbitron provides each member of a family with a Portable People Meter (PPM) that has a unique product number to monitor the listening/viewing exposure to broadcast media such as TV and radio. The family participants wear their specific PPM throughout the day, in a fashion similar to a pager. The PPM is constantly sampling the acoustic environment and listens for a unique ID code that has been embedded within a broadcast audio signal (inaudible to human hearing). An Arbitron encoder at the broadcast station generates this unique ID code. The ID code uniquely identifies the broadcast station, and when it is recorded along with the time stamp in the PPM, allows Arbitron to easily determine which program the specific family member is listening to or viewing. A base station is provided for each PPM. A PPM is placed into a base station for recharging of the PPM and downloading of the ID code and time stamp information stored in the PPM. An IR link is utilized to transmit the ID code and time stamp information from the PPM to the base station. A household hub is provided to collect via a hardwired connection, the information collected by the base stations. The information, i.e. the ID code and time stamp, is then retrieved by Arbitron. This is done by utilizing a modem connection between the hub and an Arbitron processing center. The majority of this type of media exposure is thought to occur within the home setting, but the current system cannot differentiate when a PPM is within a home setting or not, nor can it determine what percentage of the data acquired results from at home exposure. As the participant goes about their day to day activities, they become exposed to audio from a variety of sources—for example, their radio at work, in the car, or at home. Arbitron and others in this business want to know what percentage of all the data logged or collected (broadcast station ID codes and corresponding time stamps) within each individual's PPM units came from exposure within the home environment. Being able to quantify the location of data acquisition would be beneficial to Arbitron.
The CBET technology for encoding the identifying information and the PPM data acquisition technology for capturing the embedded signals are currently being tested in various pilot studies. Preliminary results indicate strong performance, however, additional information is now being requested by the sponsors regarding the location of the participant's multimedia exposure, specifically, are they in their home or not. This location data is user-specific and, therefore, cannot be encoded in the pre-broadcast signal. Other technologies have been considered in an effort to determine the participant's listening environment, but have not been found beneficial.